A reduced-nickel duplex stainless steel having abnormal strain rate sensitivity and a method of manufacturing the same

Abstract

The application discloses a kind of nickel-saving duplex stainless steel with abnormal strain rate sensitivity and its preparation method, and the main chemical components of the steel are C 0.02-0.05%, Si 0.12-0.30%, Mn 4.1-5.1%, Ni 0.18-0.26%, Cr 17.85-21.05%, N 0.2-0.35%, B 0.05-0.15%, rare earth elements 0.02-0.10%. By Mn-N alloying instead of part of Ni and other expensive elements, the cost is saved, and the austenite content and stability are adjusted. Its preparation method mainly includes smelting, hot working, cold deformation and solid solution treatment, etc. The steel shows abnormal strain rate sensitivity through tensile test, and can fully exert its TRIP effect in high-speed deformation process. Micro deep drawing forming test verifies the feasibility of its high-speed forming performance, and effectively breaks through the barrier of traditional metastable duplex stainless steel in high-speed forming process.

Description

Technical Field

[0001] This invention belongs to the field of steel material manufacturing technology, specifically relating to a nickel-saving duplex stainless steel with anomalous strain rate sensitivity and its preparation method. Background Technology

[0002] Duplex stainless steel, composed of ferrite and austenite phases, possesses excellent mechanical properties and corrosion resistance, making it widely used in marine engineering, rail transportation, and other fields. In recent years, the soaring price of Ni, a key alloying element in duplex stainless steel, has kept its cost high. To address this issue and increase cost-effectiveness, researchers have developed a series of nickel-saving duplex stainless steels. These are produced by alloying Ni with Mn and N to balance the two-phase composition and ensure mechanical properties. Furthermore, it is worth noting that these nickel-saving duplex stainless steels significantly reduce raw material costs while also metastableting the austenite phase. The TRIP (Transformation-Induced Plasticity) effect, triggered by the martensitic transformation of metastable austenite during plastic deformation, improves the work hardening ability and plasticity of duplex stainless steel. This allows for high-performance forming of complex parts, preventing localized thinning and premature failure during forming.

[0003] On the other hand, as the requirements for high efficiency in current parts manufacturing become increasingly stringent, the forming speed of complex parts is accelerating, and correspondingly, the strain rate of materials during the forming process is also increasing. However, for nickel-saving duplex stainless steels with metastable austenitic phases and / or traditional metastable austenitic stainless steels (such as 301 stainless steel), as the strain rate increases, the adiabatic temperature rise effect generated during deformation reduces the driving force of martensitic phase transformation, inhibits the martensitic phase transformation process, and significantly reduces or even eliminates the TRIP effect. This makes the high-performance forming of TRIP-type duplex stainless steel parts contradictory to the current demand for efficient manufacturing, thus limiting the large-scale industrial production of this type of material. Summary of the Invention

[0004] To address the bottlenecks in the existing technologies, this invention utilizes element ratio design to obtain an experimental steel with highly unstable austenitic properties. By leveraging the TRIP effect, it achieves anomalous strain rate sensitivity in mechanical behavior, enabling duplex stainless steel to fully utilize the TRIP effect under high-speed loading conditions and obtain better forming performance, thereby achieving high-performance forming of complex parts made of this type of stainless steel.

[0005] The main objective of this invention is to reduce the Ni and Mo content in steel through compositional optimization and a Mn-N alloying strategy, significantly lowering raw material costs and substantially reducing the mechanical stability of austenite while accelerating the deformation-induced martensitic transformation rate. Simultaneously, by actively utilizing the adiabatic temperature rise effect during high-speed forming to suppress martensitic transformation, the TRIP effect is enabled to operate over a wider strain range, further enhancing the material's mechanical properties. Particularly, it exhibits anomalous strain rate sensitivity in terms of plasticity and toughness; that is, as the strain rate increases, the material's plasticity and fracture toughness also increase.

[0006] To achieve the aforementioned objectives, this invention provides a nickel-saving duplex stainless steel with anomalous strain rate sensitivity. The duplex stainless steel comprises the following elemental composition by mass: C: 0.02%~0.05%, Si: 0.12%~0.30%, Mn: 4.10%~5.10%, Ni: 0.18%~0.26%, Cr: 17.85%~21.05%, N: 0.2%~0.35%, Cu: 0.0005%~0.001%, B: 0.05%~0.15%, rare earth elements: 0.02%~0.10%, with the balance being Fe and unavoidable impurities. Mn-N alloying replaces some expensive metal elements such as Ni to save costs and adjust the austenite content.

[0007] Nitrogen and manganese, as austenite stabilizing elements, function similarly to nickel. Manganese can control austenite stability by improving its solid solubility and influencing the critical quenching rate, further affecting phase transformation behavior. In contrast, nitrogen has a stronger effect on stabilizing austenite and can directly affect the volume fraction of austenite in duplex stainless steel. However, excessive manganese and nitrogen will make austenite more stable, failing to achieve strain rate sensitivity with anomalous performance trends or even effectively exerting its TRIP effect. Therefore, to balance the two-phase ratio and adjust austenite stability, this invention controls the manganese content at 4.10%~5.10% and the nitrogen content at 0.2%~0.35%.

[0008] An appropriate amount of boron can effectively control the oxidation resistance of materials and regulate grain boundary characteristics, resulting in superior performance under high-temperature deformation. In this invention, its content is controlled at 0.05%~0.15%.

[0009] Furthermore, trace amounts of rare earth elements can control inclusions and purify molten steel to further improve its properties. On the other hand, they also contribute to improving the material's corrosion resistance and high-temperature performance. In this invention, the rare earth element content is controlled at 0.02% to 0.10%.

[0010] Stability evaluation coefficient of the nickel-saving duplex stainless steel with anomalous strain rate sensitivityM d30 The temperature range is 66~76℃. Stability evaluation coefficient. M d30 This refers to the temperature at which 50% of austenite transforms into martensite when the true strain reaches 0.3. M d30 The larger the value, the worse the austenite stability. M d30 The calculation formula is as follows: M d30 (°C) = 551 - 462 (ω) C +ω N -9.2ω Si -8.1ω Mn -13.7ω Cr -29(ω Ni +ω Cu ) Where, ω i This indicates the content of element i in austenite.

[0011] A method for preparing the above-mentioned nickel-saving duplex stainless steel with anomalous strain rate sensitivity, the method comprising the following process steps: S1. Smelting and hot working (forging): Smelting is carried out in a 20 kg vacuum induction furnace according to the weight percentage. The ingot is smelted and cast into a billet by the above-mentioned nickel-saving duplex stainless steel chemical composition ratio. Then, it is forged into a slab by free forging. The billet temperature is controlled at 1100~1200℃ and the final forging temperature is ≥950℃. After air cooling, the initial plate with a thickness of 3 mm is obtained by cutting.

[0012] S2. Cold Deformation (Rolling) Treatment: The material is cold rolled to 1.5 mm in multiple passes (total deformation is approximately 50%). During the cold rolling process, the material needs to be annealed to eliminate internal stress and prevent cracks from occurring during subsequent deformation. The annealing temperature is 600~660℃, and the time is 15~30 min. After air cooling to room temperature, the subsequent cold deformation treatment continues.

[0013] S3. Solution Treatment: Solution treatment effectively reduces strain hardening, residual stress, and texture effects after cold deformation, allowing the material to regain a uniform microstructure and mechanical properties. Furthermore, it promotes interphase element diffusion to regulate the phase composition and distribution of the material and modulates austenite stability, placing the material in a highly unstable state, making it more prone to martensitic transformation and exerting its TRIP effect. The samples were solution treated at 1000℃~1060℃ for 20~40 min, then rapidly water-cooled to obtain highly unstable, nickel-saving (nickel-saving) duplex stainless steel.

[0014] S4. Sample performance testing and analysis: The tensile mechanical properties of the material under different strain rates were analyzed by room temperature tensile tests, and the excellent high-speed forming performance of the sample and the effectiveness of the manufacturing method were verified by micro-deep drawing forming tests.

[0015] In the above technical solution, further, before the hot working (forging) described in step S1, the ingot is first heated to 1100~1200℃ and held for 2 hours, and the billet temperature is 1150℃.

[0016] Furthermore, in step S2, the total deformation amount of cold rolling is 48-52%, and after cold rolling deformation of 25%, annealing is performed at a temperature of 600-660℃ and a holding time of 15-30 min.

[0017] Furthermore, after cold rolling deformation, step S2 involves annealing at a temperature of 650°C for 20 minutes.

[0018] Furthermore, the solution treatment temperature in step S3 is 1050℃, and the holding time is 30 min.

[0019] Furthermore, the strain rate test range for the tension described in step S4 is 10. -3 ~10 1 s -1 Until fracture failure. The micro-drawing verification test was set with a tensile rate range of 10... -3 ~10 0 mm / s, until the load drops sharply (premature damage and failure) or gradually decreases to a low level (the formed part is completed).

[0020] The above technical solution achieves cost savings by using Mn-N alloyed duplex stainless steel, while also controlling the austenite content and achieving its high instability through heat treatment processes.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: ① Reduced raw material costs: This technical solution uses more inexpensive metals such as Mn and N to replace the expensive metals such as Ni commonly used in traditional duplex stainless steel. This significantly reduces raw material costs, making the production process more economical and efficient. Furthermore, it allows for better control of the residual austenite content and mechanical stability at room temperature, providing better conditions for the continued effectiveness of the TRIP effect.

[0022] ② The addition of rare earth and boron elements can further purify molten steel, improve its hot working performance, and enhance its resistance to intergranular corrosion and high-temperature creep resistance.

[0023] ③ Achieving high material instability: By alloying Mn-N and combining it with heat treatment, the austenite phase becomes highly unstable, which makes it easier to trigger the TRIP effect and achieve strain-induced martensite transformation during room temperature deformation.

[0024] ④ The mechanical properties exhibit anomalous strain rate sensitivity: By regulating the stability of austenite and taking into account the adiabatic temperature rise effect, it achieves a strain rate sensitivity that is unusual compared to traditional metastable stainless steel or TRIP steel. Furthermore, its plasticity and toughness show a significant upward trend with increasing strain rate, enabling it to fully utilize the TRIP effect and obtain superior mechanical properties under rapid deformation. At the same time, it avoids the problem of significantly reduced fracture resistance due to excessively fast martensite transformation rate.

[0025] ⑤ Superior high-speed forming performance: Compared with traditional TRIP steel or TRIP-type duplex stainless steel, this invention breaks through the barrier of local damage or premature fracture failure during high-speed forming at room temperature, and can meet the requirements of superior forming performance under high-speed forming.

[0026] In summary, the material described in this invention utilizes the extremely low mechanical stability of the austenite phase in a nickel-saving duplex stainless steel, giving it an anomalous strain rate sensitivity. This makes such metastable materials more suitable for achieving high formability at high strain rates, providing a new technological approach for developing metastable duplex stainless steel materials more suitable for high-speed forming. Attached Figure Description

[0027] Figure 1 Image of the initial microstructure of the nickel-saving duplex stainless steel prepared in Example 1; Figure 2 Mechanical property curves of the nickel-saving duplex stainless steel prepared in Example 1 at different strain rates; Figure 3 The mechanical property curves of duplex stainless steel prepared as a comparative example at different strain rates are shown. Figure 4 Example 1 ( Figure 4 a) and comparative examples ( Figure 4 b) Comparison curves of tensile properties of the prepared duplex stainless steel at room temperature; Figure 5 SEM images of the fracture surfaces of the nickel-saving duplex stainless steel prepared in Example 1 after tensile fracture at different strain rates; Figure 6 The graph shows a comparison of the strength-ductility product of stainless steel materials as a function of strain rate in Example 1, the comparative example, and the prior art. Figure 7 The image shows a comparison of the forming effects of the nickel-saving duplex stainless steel prepared in Example 1 at different rates. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but this does not limit the invention in any way. To avoid redundancy, unless otherwise specified, the raw materials used in the following embodiments are all commercially available products, and the methods used are all conventional methods unless otherwise specified.

[0029] Example 1 A nickel-saving duplex stainless steel with anomalous strain rate sensitivity, the duplex stainless steel comprising the following elemental composition by mass: C: 0.03%, Si: 0.2%, Mn: 4.9%, Ni: 0.23%, Cr: 19.3%, N: 0.28%, Cu: 0.001%, B: 0.06%, rare earth elements: 0.10%, with the balance being Fe and unavoidable impurities.

[0030] A method for preparing nickel-saving duplex stainless steel with anomalous strain rate sensitivity, the specific process steps (taking rolled sheet as an example) are as follows: S1. Smelting and hot working (forging): Smelting is carried out in a 20 kg vacuum induction furnace. The above-mentioned elements are smelted and cast into ingots, and then free forging is used to form slabs. The initial heating temperature is controlled at 1150℃, and the final forging temperature is ≥950℃. After air cooling, an initial sample with a thickness of 3 mm is obtained by cutting. S2. Cold deformation (rolling) treatment: The material is subjected to cold deformation (cold rolling) treatment, rolled to 1.5 mm (deformation amount is about 50%), and annealing is performed when the deformation reaches 25% during the process. The annealing temperature is 650℃ and the time is 20 min. After air cooling to room temperature, the subsequent rolling treatment is carried out. S3. Solution treatment: The rolled sample is solution treated by heating at 1050℃ for 30 min, and then the sample is taken out and quickly water-cooled to finally obtain a highly unstable, economical duplex stainless steel.

[0031] S4. Sample Performance Testing and Analysis ① Initial material microstructure: The material sample prepared in Example 1 was cut and polished, and its initial microstructure was observed under a microscope. Figure 1 As shown. By Figure 1 It can be seen that the phases of the material used in this invention are evenly distributed along the rolling direction. The two phase structures are face-centered cubic (about 60%) and body-centered cubic (about 40%), respectively. The material is relatively pure inside and there are no precipitated phases or impurities.

[0032] ② Tensile mechanical properties and high-speed forming performance testing: Tensile specimens from Example 1 were cut and subjected to uniaxial tensile mechanical properties and real-time adiabatic temperature rise evaluation tests using a Gleeble-3800 thermodynamic simulator. The test environment was room temperature, and the strain rate was controlled by the tensile rate, with a test range of 10. -3~10 1 s -1 Until fracture failure, during which time an extensometer is used to monitor the displacement of the gauge length segment in real time to obtain the material's mechanical property curves, such as... Figure 2 As shown.

[0033] Example 2 A nickel-saving duplex stainless steel with anomalous strain rate sensitivity, the duplex stainless steel comprising the following elemental composition by mass: C: 0.033%, Si: 0.22%, Mn: 4.9%, Ni: 0.21%, Cr: 19.9%, N: 0.24%, Cu: 0.001%, B: 0.06%, rare earth elements: 0.10%, with the balance being Fe and unavoidable impurities.

[0034] The preparation method of nickel-saving duplex stainless steel with anomalous strain rate sensitivity (taking rolled sheet as an example) described in Example 2 has the same process steps as in Example 1.

[0035] Example 3 A nickel-saving duplex stainless steel with anomalous strain rate sensitivity, the duplex stainless steel comprising the following elemental composition by mass: C: 0.035%, Si: 0.18%, Mn: 5.0%, Ni: 0.22%, Cr: 19.1%, N: 0.30%, Cu: 0.001%, B: 0.06%, rare earth elements: 0.10%, with the balance being Fe and unavoidable impurities.

[0036] The preparation method of nickel-saving duplex stainless steel with anomalous strain rate sensitivity (taking rolled plate as an example) described in Example 3 has the same process steps as in Example 1.

[0037] Comparative Example A conventional, energy-saving metastable duplex stainless steel was used as a comparative example, which comprises the following chemical elemental composition by mass percentage: C: 0.06%, Si: 0.78%, Mn: 2.94%, Ni: 0.97%, Cr: 19.19%, N: 0.21%, Cu: 1.86%, with the balance being Fe and unavoidable impurities.

[0038] The comparative example also uses a plate as an example, and its sample preparation method is the same as that in Example 1.

[0039] To illustrate the difference in stability between the embodiments of the present invention and the comparative examples, the following methods are used: M d30 (The temperature at which 50% of austenite transforms into martensite when the true strain reaches 0.3) is used as a stability evaluation coefficient to describe this, as is well known. M d30The larger the value, the worse the austenite stability. The chemical composition of the austenite phase in the examples and comparative examples at the corresponding solution temperature (1050℃) was calculated using thermodynamic software and is shown in Table 1. The respective chemical compositions of the austenite phase in the examples and comparative examples were also calculated. M d30 That is, equation (1).

[0040] M d30 (°C) = 551 - 462 (ω) C +ω N -9.2ω Si -8.1ω Mn -13.7ω Cr -29(ω Ni +ω Cu (1) Where, ω i This indicates the content of element i in austenite. Calculations were performed to obtain the values ​​of the examples and comparative examples. M d30 And listed in Table 1. As can be seen from Table 1, the embodiments... M d30 The austenite stability is significantly higher than that of the comparative example, therefore it is less stable than the comparative example, making it more susceptible to strain-induced martensite transformation and more likely to exhibit the TRIP effect.

[0041] Table 1. Austenite content (wt.%) and stability evaluation parameters of the examples and comparative examples M d30 (°C)

[0042] The prepared comparative specimens were subjected to strain rate sensitivity tests using the same equipment as in the example. It should be noted that the TRIP effect in the comparative specimens is significant at a strain rate of 10... 0 s -1 Since the adiabatic temperature rise effect has completely suppressed the plasticizing effect, the strain rate control range for the proportional test is 10. -4 ~10 0 s -1 Similarly, stress-strain curves at different strain rates were obtained, such as... Figure 3 As shown. Further, the mechanical properties of Example 1 and the comparative example were obtained based on the stress-strain curve data, as follows. Figure 4 As shown.

[0043] On the other hand, the fracture morphology of Example 1 after tensile fracture was observed by scanning electron microscopy (SEM), and three strain rate conditions (10) were selected. -3 s -1 10 -1 s-1 and 10 1 s -1 The analysis focuses on the strain rate sensitivity of abnormal mechanical properties from a fracture perspective, and discusses this. Figure 5 As shown.

[0044] Furthermore, to illustrate the uniqueness of the method of this invention, the strength-ductility product of traditional metastable duplex stainless steel and austenitic stainless steel used in other published studies was compared with the strain rate variation trend, such as... Figure 6 As shown.

[0045] Finally, the forming results of Example 1 at different deformation rates were analyzed through micro-deep drawing verification tests, with the stretching rate range set at 10. -3 ~10 0 mm / s, until the load drops sharply and instantaneously (premature damage and failure) or gradually decreases to a low level (the formed part is completed), such as Figure 7 As shown.

[0046] Example 1 (see Figure 2 and Figure 4 a) The mechanical properties under tensile test conditions reflect a Ni-retaining duplex stainless steel that differs from traditional stainless steels with a metastable austenitic phase (see comparative example). Figure 3 and Figure 4 b) and traditional metastable austenitic stainless steels (such as 304 stainless steel, etc.). Figure 6 The anomalous strain rate sensitivity of the material (as shown in b) indicates that its mechanical properties, especially plasticity, increase continuously with increasing strain rate, which is unusual compared to the gradual decrease in mechanical properties of traditional metastable materials. The underlying principle is that at low strain rates, the highly unstable austenite rapidly transforms into hard martensite due to deformation, leading to premature damage or even brittle fracture at localized locations, preventing the effective utilization of the TRIP effect over a wider strain range. At high strain rates, however, the adiabatic temperature rise enhances the stability of austenite, gradually suppressing some strain-induced martensite phase transformations as strain increases, maintaining uniform deformation. Furthermore, the TRIP effect continues to act over a wider strain range, resulting in higher plasticity and even ductile-brittle transformation to ductile fracture under temperature influence. This is evident from the elongation (… Figure 4 a) It can also be seen that it increases continuously with the increase of strain rate.

[0047] Figure 5 It demonstrates the performance at low rates (10 -3 s -1 The fracture surface exhibits typical brittle cleavage fracture characteristics; at medium speeds (10... - 1 s -1 At high speeds (10), both brittle and tough characteristics coexist; while at high speeds (10), brittleness and toughness are present simultaneously.1 s -1 At this stage, the fracture is characterized primarily by ductile fracture features such as dimples and pores. That is, at 10... -1 s -1 The ductile-brittle transition occurs during this process, which is the main reason why the mechanical properties of this invention exhibit anomalous strain rate sensitivity.

[0048] Figure 6 This demonstrates that the comparative example, consistent with existing traditional metastable duplex stainless steel and austenitic stainless steel technologies, exhibits a continuous decrease in overall mechanical properties with increasing strain rate. Its TRIP effect is also weakened due to the adiabatic temperature rise, failing to achieve superior plasticity under high-speed deformation conditions. Conversely, the strength-ductility product of the embodiments of this invention continuously increases with increasing strain rate. Although its performance is poor under quasi-static deformation, its overall performance under high-speed deformation is far superior to that of the comparative example and other materials used in the studies, exhibiting a higher strength-ductility product.

[0049] Figure 7 The verification test results can demonstrate that at low forming speeds (drawing rate 10), -3 and 10 -2 Due to the extreme instability of austenite, the rapid phase transformation at a deformation rate of 10 mm / s led to premature fracture failure, resulting in obvious cracks on the surface of the formed part. Subsequent measurements of the distance from the crack to the bottom of the cup revealed that this distance gradually increased with increasing deformation rate (from 1.18 mm to 1.81 mm, corresponding to 10 mm / s). -3 mm / s and 10 -2 With a drawing speed of mm / s, the forming depth is increased, resulting in better forming performance. This continues until high-speed forming (drawing rate 10...) 0 At a drawing speed of mm / s, no cracks appeared, and a complete cylindrical part could be obtained. Furthermore, the loading curve shows that even at low forming speeds, both the loading load and the punch displacement increase with the drawing rate, indicating that the material gains greater resistance to deformation as the deformation rate increases. This further demonstrates the feasibility of the present invention, namely that this type of highly unstable metastable duplex stainless steel can effectively meet the high efficiency requirements of actual production conditions.

[0050] Furthermore, the performance of Examples 2 and 3, after experimental testing, also exhibited this anomalous strain rate sensitivity behavior, demonstrating the ability to effectively utilize the TRIP effect to achieve superior forming results under high-speed loading. Therefore, it can be concluded that the elemental ratios combined with the heat treatment process can achieve the technical effect of obtaining a highly unstable austenitic phase in this type of metastable duplex stainless steel, utilizing the adiabatic temperature rise effect under high-speed deformation conditions to obtain superior performance.

[0051] In summary, Examples 1-3, compared with the comparative examples of traditional metastable duplex stainless steel and other materials used in studies, show significant advantages in terms of plasticity gain and forming effect under high-speed deformation conditions. This verifies that the highly unstable, economical metastable duplex stainless steel prepared by this invention can effectively utilize the adiabatic temperature rise effect to fully exert its TRIP effect during high-speed deformation. The resulting anomalous strain rate sensitivity makes it more adaptable to actual high-speed processing forming conditions than traditional materials.

[0052] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A nickel-saving duplex stainless steel with anomalous strain rate sensitivity, characterized in that, The duplex stainless steel comprises the following elemental composition by mass: C: 0.02%~0.05%, Si: 0.12%~0.30%, Mn: 4.10%~5.10%, Ni: 0.18%~0.26%, Cr: 17.85%~21.05%, N: 0.2%~0.35%, Cu: 0.0005%~0.001%, B: 0.05%~0.15%, rare earth elements: 0.02%~0.10%, with the balance being Fe and unavoidable impurities; Stability evaluation coefficient of the nickel-saving duplex stainless steel M d30 The temperature range is 66~76℃; stability evaluation coefficient M d30 It refers to the temperature at which 50% of austenite transforms into martensite when the true strain reaches 0.3, and the unit is ℃; M d30 The larger the value, the worse the austenite stability. M d30 The calculation formula is as follows: M d30 =551-462(ω C +oh N )-9.2h Si -8.1h Mn -13.7h Cr -29(oh Ni +oh Cu ) wherein ω i represents the content of the i element in the austenite; The method for preparing the nickel-saving duplex stainless steel with anomalous strain rate sensitivity includes the following process steps: S1 Smelting and Hot Working: The nickel-saving duplex stainless steel is smelted and cast into ingots using the chemical composition ratio of the above-mentioned nickel-saving duplex stainless steel, and then forged into slabs. The initial forging temperature is 1100℃~1200℃, the final forging temperature is ≥950℃, and after air cooling, it is cut to obtain an initial plate with a thickness of 3 mm. S2 cold rolling deformation treatment: cold rolling to 1.5 mm in multiple passes, annealing during cold rolling, air cooling to room temperature and then continuing deformation treatment; S3 solution treatment: Hold at 1000℃~1060℃ for 20~40 min, then remove and water cool to obtain nickel-saving duplex stainless steel; S4 Sample Performance Testing and Analysis: Analysis of the tensile mechanical properties of the material under different strain rates, and verification of the high-speed forming performance of the material by micro-deep drawing test.

2. A method for preparing nickel-saving duplex stainless steel with anomalous strain rate sensitivity as described in claim 1, characterized in that, The process includes the following steps: S1 Smelting and Hot Working: The nickel-saving duplex stainless steel is smelted and cast into ingots using the chemical composition ratio of the above-mentioned nickel-saving duplex stainless steel, and then forged into slabs. The initial forging temperature is 1100℃~1200℃, the final forging temperature is ≥950℃, and after air cooling, it is cut to obtain an initial plate with a thickness of 3 mm. S2 cold rolling deformation treatment: cold rolling to 1.5 mm in multiple passes, annealing during cold rolling, air cooling to room temperature and then continuing deformation treatment; S3 solution treatment: Hold at 1000℃~1060℃ for 20~40 min, then remove and water cool to obtain nickel-saving duplex stainless steel; S4 Sample Performance Testing and Analysis: Analysis of the tensile mechanical properties of the material under different strain rates, and verification of the high-speed forming performance of the material by micro-deep drawing test.

3. The preparation method according to claim 2, characterized in that, Before the hot working described in step S1, the ingot is heated to 1100~1200℃ and held for 2 hours; the billet temperature is 1150℃.

4. The preparation method according to claim 2, characterized in that, The total deformation amount of cold rolling in step S2 is 48~52%. After cold rolling deformation of 25%, annealing is performed at a temperature of 600~660℃ and a holding time of 15~30 min.

5. The preparation method according to claim 2, characterized in that, After cold rolling deformation, step S2 involves annealing at a temperature of 650°C for 20 minutes.

6. The preparation method according to claim 2, characterized in that, The solution treatment temperature in step S3 is 1050℃, and the holding time is 30 min.

7. The preparation method according to claim 2, characterized in that, The strain rate test range for the tensile stress described in step S4 is 10. -3 ~10 1 s -1 Until it breaks and fails.

8. The preparation method according to claim 2, characterized in that, The micro-deep drawing test in step S4 is set with a tensile rate range of 10. -3 ~10 0 mm / s.

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